Uncontrolled light can be wasted in lighting areas around the target area to be lighted, and contributes to unwanted “night lighting” which can interfere with the preservation and protection of the nighttime environment and our heritage of dark skies at night. Uncontrolled light also necessitates generation of greater amounts of light to meet the lighting requirements in the target area requiring higher power equipment and energy consumption to provide the target area with the desired amount of light.
The Illuminating Engineering Society of North America (“IESNA”) defines various light distribution patterns for various applications. For example, the IESNA defines Roadway Luminaire Classification Types I-V for luminaires providing roadway and area lighting. The IESNA defines other informal classifications for light distribution patterns provided by roadway and area luminaires as well as light distribution patterns for other applications. These and other light distribution patterns can be obtained by directing light emitted from the one or more light sources in a luminaire. This holds true regardless of light source.
When the light source is one or more LEDs (or other small light sources), it is known to distribute the emitted light by one or more reflectors associated with one or more light sources. One example of a reflector system for distributing light emitted from LEDs is disclosed in U.S. patent application Ser. No. 12/166,536 filed Jul. 2, 2008, the entirety of which is incorporated herein by reference.
Improvements in LED lighting technology have led to the development by Osram Sylvania of an LED having an integral optic that emits a significant portion of the LED light bilaterally and at high angle α (about 60°) from nadir, which is available as the Golden DRAGON® LED with Lens (hereinafter, “bilateral, high angular LED”). FIG. 1A is a representation of the bilateral, high angular LED 252 showing the direction and angle of the lines 255 of maximum light intensity emitted by the LED, substantially in opposed designated ±Z axes. Progressively and significantly lower levels of light intensity are emitted at angles in the Y-Z plane diverging from lines 255 and along vectors directed toward the transverse direction (±X axes) normal to the image of the figure. The radiation characteristics of the LED 252 are shown in FIG. 1B. These or other LEDs (or other light sources) can be arranged in a lighting apparatus in conjunction with a reflector system to distribute the light emitted from the light sources (which include, by definition, LEDs) to efficiently meet the light distribution needs of various applications with a minimum of wasted light.